The invention relates to a process and a device for tapping a submerged pipe, for example a pipe for conveying petroleum products. The tapping operation may be for the purpose of attaching a branch pipe to a main pipe or in of replacing a damaged pipe section. In the latter case, the connection of a new section to pipe ends can be carried out in accordance with various known joining processes, in particular by welding under normal pressure or under excess pressure, by bonding or by mechanical connection, and the invention essentially concerns the preparatory stage of the actual connection, that is to say to the preparation of the pipe ends which will remain after removal of the section to be replaced.
It is known to carry out various kinds of underwater work using divers equipped with hand tools. This procedure involves many risks and is not suitable if the pipe is at a depth inaccessible by divers. It has been proposed to use a submarine vehicle which has all the tools and operating means required for the various operations permitting the replacement of a pipe section, which, equipped with feet for resting on the sea bed, settles above the tapping point, and which is linked to the surface by an umbilical cable. A vehicle of this type has a very complicated design, does not easily adapt to different conditions of use and becomes immobilised by the breakdown of only one of its many devices.
It has also been proposed to mount girders on the pipe by means of clamping rings so that a support can move on the girders. The support is equipped with a plurality of various remote-controlled tools designed to perform the necessary operations. However, it is difficult to mount these various tools, on the single support, and oftentimes it is impossible in operating all these various tools to obtain the best working conditions and sufficient speed. Moreover, in the case of a pipe covered with concrete, mounting the girders to a pipe presupposes that the pipe has been stripped of concrete beforehand, and this method therefore excludes the concrete-stripping operation from the operations carried out according to the method.